/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.core.io;

import org.apache.flink.annotation.Internal;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.DataOutputView;

import java.io.IOException;
import java.util.Arrays;

/**
 * This is the abstract base class for {@link IOReadableWritable} which allows to differentiate between serialization
 * versions. Concrete subclasses should typically override the {@link #write(DataOutputView)} and
 * {@link #read(DataInputView)}, thereby calling super to ensure version checking.
 */
@Internal
public abstract class VersionedIOReadableWritable implements IOReadableWritable, Versioned {

	private int readVersion = Integer.MIN_VALUE;

	@Override
	public void write(DataOutputView out) throws IOException {
		out.writeInt(getVersion());
	}

	@Override
	public void read(DataInputView in) throws IOException {
		this.readVersion = in.readInt();
		resolveVersionRead(readVersion);
	}

	/**
	 * Returns the found serialization version. If this instance was not read from serialized bytes
	 * but simply instantiated, then the current version is returned.
	 *
	 * @return the read serialization version, or the current version if the instance was not read from bytes.
	 */
	public int getReadVersion() {
		return (readVersion == Integer.MIN_VALUE) ? getVersion() : readVersion;
	}

	/**
	 * Returns the compatible version values.
	 *
	 * <p>By default, the base implementation recognizes only the current version (identified by {@link #getVersion()})
	 * as compatible. This method can be used as a hook and may be overridden to identify more compatible versions.
	 *
	 * @return an array of integers representing the compatible version values.
	 */
	public int[] getCompatibleVersions() {
		return new int[] {getVersion()};
	}

	private void resolveVersionRead(int readVersion) throws VersionMismatchException {

		int[] compatibleVersions = getCompatibleVersions();
		for (int compatibleVersion : compatibleVersions) {
			if (compatibleVersion == readVersion) {
				return;
			}
		}

		throw new VersionMismatchException(
			"Incompatible version: found " + readVersion + ", compatible versions are " + Arrays.toString(compatibleVersions));
	}
}
